Principle and simulation of a 5-phase bearingless permanent magnet-type synchronous motor

Two magnetic fields produce radial force on rotor when the difference of their pole pair numbers is 1. Based on this principle, this paper introduces the bearingless motor with a single set of 5-phase windings. The MMF waveform produced by multiphase windings is analyzed, based on which the winding configuration of 5-phase bearingless motor is introduced. The two needed magnetic fields are produced by feeding two groups of currents which are projected into 2 orthogonal d-q planes respectively. The inductance matrices, considering air gap eccentricity, are calculated with the Modified Winding Function Method. The radial force analytical model is deduced by virtual displacement, and its results are validated by FEA. The mathematical model of the new bearingless machine is set up, and simulation results indicate that stable levitation can be achieved.